Resonance Trimming in Dielectric Resonant Metasurfaces

The field of metasurfaces is rapidly growing. Nowadays, metasurfaces are considered at the front of artificial optical materials. With metasurfaces, it is possible to control the properties of light for variety of applications, from beam shaping, structural colors, and polarization control to tight focusing, scanning, spatial and spectral filtering, etc. One of the major challenges in the construction of metasurfaces is the need for precise control over their dimensions and consequently their spectral response. In this paper, we demonstrate an approach for postfabrication trimming of dielectric metasurfaces consisting of amorphous silicon layer on top of a quartz substrate, by using local oxidation of silicon technique. The oxidation effectively reduces the radius of the silicon disk, resulting in a blue shift in the observed spectral response. Blue shift of up to 100 nm is demonstrated. Relaxing fabrication tolerances and enabling post-processing techniques is expected to play an important role in promoting the scientific advances of metasurfaces into viable and useful technology. We thus believe that the demonstrated approach will provide an additional important tool to the rapidly developed toolkit of metasurface science and technology.